Reversing the Arrow of Causation

Mijara T’ran:

You’ve likely heard the skeptic’s cautionary advice that correlation is not causation. We should be wary whenever someone observes that two things occur together, therefore one causes the other. Unfortunately, this kind of shaky logic is extraordinarily common these days. Rigorous experimentation, where you hold as many variables constant as possible and then change the factor you’re studying to observe its effects, is difficult, expensive, and time-consuming. This holds especially true in the area of health, where the subjects are people with their myriad habits and lifestyles (lots of variables to control for!), and the effects under study might not change in measurable ways for years or decades.

To get around these difficulties, researchers turn to an easier, cheaper, faster alternative: data mining! We have accumulated a wealth of data on innumerable facts of people’s lives, especially their health. By comparison to clinical trial and experiment, it’s easy to sift that data and narrow down to the variables we’re interested in and see how they are interrelated. The drawback, as you might have guessed, is that the output is all correlational data. We can see which lines on the graph climb at the same pace, but without isolating them and seeing what happens to one when we change the slope of the other, it’s very difficult to be sure which one of them is causing the other. Indeed, they might not be related by cause and effect at all, but could both be effects of some third variable.

Here’s a trick I’ve adopted to help spot bad correlation-causation claims, a critical-thinking shortcut that’s quick to apply and often insightful. Ask yourself: “Is it plausible that what they’re claiming is the cause might actually be the effect, and vice versa?” People doing correlational studies frequently don’t consider the possibility, simple though it is! Here are a few examples to get you thinking.

The correlation: People who are overweight eat a lot and don’t exercise much.
The claim: Overeating and lack of exercise cause weight gain.
The flip: Gaining weight causes you to eat more and exercise less.

If you’ve read any of this blog up to now, you’re familiar with this one. It looks weird at first, since we’re so inundated with the message that fat people are fat because of their bad behavior. But it turns out this flip brings immense insight when investigated. In fact, there’s a different cause to weight gain: the hormone insulin, whose action ramps up when we eat carbohydrates, the type of food energy found in staples like bread and pasta. The metabolic effects of weight gain in turn slow down our desire to exercise and prompt us to eat more. Stop eating carbs, insulin quiets down, you lose weight, and your appetite decreases and your energy for exercise returns!

The correlation: People who sit a lot during their days have higher incidence of obesity, diabetes, and heart disease.
The claim: Sitting makes you more prone to get sick.
The flip: Getting sick makes you sit more.

A while ago, a scary infographic made the rounds of the Internet, saying how sitting is killing you. Its message prompted me to get a standing desk at work and to set one up at home. But after learning about the causation-flip trick, I came back to the topic and tried it out: great Primes, it’s so obvious! People who are obese, diabetic, or have weak hearts are going to have more trouble getting up and staying active than people not suffering from those conditions. So of course you’re going to see sitting time climb along with the incidence of those conditions. Now, there are valid points in that article, notably the pieces that come from experimental observation rather than correlational leap. But the graphic’s biggest punch comes from something that, having engaged this trick, seems sketchy.

Try it out on your favorite topics! What if we’re not getting stupider because of our cell phones, but we’re more enthralled by our cell phones because some third factor is weakening our brains? What if your shiftless cousin didn’t stop looking for work because he was lazy, but got lazy (depressed, lethargic) because of his inability to find work? It won’t always yield some new insight, but the occasions when it does may surprise you!


Diet Myths and the Puritan Ethic

Mijara T’ran:

One of the most insidious things about our entrenched set of diet myths is how nicely they dovetail with the other great American myth: that hard work and self-sacrifice cure all ills, raising folk up by their bootstraps from poor house to White House. The great USian traditions of moralizing and anti-intellectualism make the “gluttony and sloth” narrative hard to dislodge.

If we accept that the cycle of carbohydrate intake, insulin resistance, and hormone production in fat tissue describes the progress of obesity and diabetes, then we must accept that we overeat and stop exercising because we get fat, not vice versa. And if we accept that, then we must give up looking at overweight people and saying, “It is their fault for eating so much and sitting around all day! I’m thin, so you can see how much better a person I am than they!”

If we accept that human biology is not well adapted to a diet heavy in grain, then that would admit a victory of scientific understanding over tradition. And we do so hate to yield ground to science! We would prefer to put our faith in the majority, in the old saws of past decades, no matter how ineffectual or thoroughly debunked. (Ever notice how, rather than refute the science behind or effectiveness of e.g. Atkins, detractors dismiss his work as “not mainstream,” how “most nutritionists” don’t subscribe to it?) I’ve always been told that whole grains and fruits will grant me long life; how could that possibly be misleading?

If we accept that there is more going on behind weight gain than “calories in minus calories out,” then that would downplay the mighty power of exercise. No pain, no gain! To get better, you must punish yourself, redouble your efforts, submit to the yoke! Hard work is the American way, the only route to success. Eating more fatty meat and eggs, and cutting out breads and pastas… there is nothing virtuous in that. Even if it works!

It’s not the cause of our current misapprehensions about food and health, exactly (the McGovern Report takes most credit for that), but it does make it harder for us to change course, as a nation. It is far too popular an American hobby to pass judgment on others, to sneer at science, to thump our chests about hard work, for us to let go of it easily. And yet if we do let go of those tendencies, here, we will all be healthier as a result.

Diets are Difficult!

Mijara T’ran:

Bring up any diet strategy, and you’ll hear people say, “it doesn’t work,” or “dieting is really hard.” Chances are, they’re right! But different diets are tricky or ineffective in different ways. The details thereof tell a lot about how valuable a diet’s ideas are, and what if anything we can do to make it work.

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Unbalanced, Part 1: There’s No Such Thing as a Good Carb

In many of the topics covered on this blog, I can come across as “extreme” or “radical” in my views. Sometimes this is a criticism well deserved; there have been times when I’ve gotten into a defensive stance and said uncharitable, overreaching things. Beyond that, though, I tend to come across that way for two reasons. One, I can be a stickler for logic and literal truth when it comes to these discussions–I’m reluctant to assent to a thing if it can be construed to mean something I don’t believe is correct. Sometimes, that means I reject such bland truisms as “everything in moderation” or “what you need is balance,” making me look like something of a nutjob! Secondly, I have a perfectionist, idealistic personality (a One on the enneagram, for those who, like me, enjoy such pop-psych toys), which pushes me to a “things could always be better”, never satisfied, style of thinking. That inability to say “good enough” can seem like extremism.

In this series of posts, I’ll talk about the ways these ideas are radical, and the ways they aren’t. I’ll start off by articulating some shocking, out-there statement I basically agree with. I’ll bring up a few common objections to the position and rebut them as best I can. Then I’ll close with an explanation of how in practice it’s not so overkill as it sounds, rein in the attitude with considerations of practicality, or the like.

First up are my gonzo moon ideas about nutrition. Here we go!

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